Reproduction of photographs on ceramics



Aug. 2, 1960 M. FAMELY ETA!- 2,947,625

REPRODUCTION OF PHOTOGRAPHS on CERAMICS Filed Nov. 8, 1954 2 Sheets-Sheet 1 FIG.2

INVENTORS MAX FAMEL GE RGE F.LEYONMXRK ATTORN EY Aug. 2, 1960 M. FAMELY EI'AL 2,947,626

REPRODUCTION OF PHOTOGRAPHS on CERAMICS Filed Nov. 8, 1954 2 Sheets-Sheet 2 FIG.4

lNVENTORS MAX FAMELY GEORGE FLEEYONMARK ATTORNEY United States REPRODUCTION OF PHOTOGRAPHS ON CERAMICS Max Famely, Linden, NJ., and George F. Leyonmark, Huntington, N.Y., assignors, by mesne assignments, to Photo Ceramics Corporation, Long Island City, N.Y., a corporation of New York Filed Nov. 8, 1954, Ser. No. 467,465

4 Claims. 01. 96-34) This invention relates generally to the photographic arts and is more particularly concerned with methods and means for recording and preserving a photographic image on a ceramic base.

In photographic reproduction processes generally, there have been many varied proposals for transferring the exposed emulsion layer from its original base or support to a new base or support for permanent afiixing thereto. It is recognized in the photographic art that a sensitized emulsion layer after exposure to activating radiations can be removed from its original support and placed upon a new support and can thereafter be developed and/or fixed to produce a permanent image on the new support. In the ceramic art, and particularly with respect to the use of tiles and like ceramic surfaces for decorative purposes, there has been a long felt want for reproduction of a direct photographic reproduction. Decalcomanias, which are lithographic reproductions, have been effectively used for decorating ceramic surfaces but to the best of our knowledge, direct photographic reproduction on ceramic tiles and like ceramic surfaces has not been successfully practiced. This is particularly the case when the type of base material is contemplated which is to be fired to high temperatures to fix a permanent glaze thereover, this being a requisite of some ceramic materials.

In such cases, when a design is to be applied to the ceramic material the normal procedure is to take a biscuit or bisque of the clay material namely, a once fired ceramic piece which is in a porous condition at this point, apply the desired design by means of a pigmented chemical composition usually referred to as an underglaze, which often includes a suitable binder or tfixingmedium, apply thereover a usually non-pigmented chemical composition known as a glaze and then heat-treat the treated bisque to a high temperature and for a time to set the glaze, namely to fire the piece in accordance with conventional practice.

The present invention generally is concerned with such procedure and applies thereto the unique step of utilizing a photographic image in place of the underglaze design.

It is accordingly the principal object of the present invention to provide a process and means for producing a finished heat-treated ceramic piece having a photographically reproduced permanent image thereon.

It is a further object of the invention to provide a method and means for producing photographically an image on a porous base of ceramic material directly from a photographic original for the purpose of subsequently fixing said image on the ceramic material.

A further important object of the invention is to provide a new form of photographic emulsion on a temporary support suitable for use in preparing a photographic image for application on a porous ceramic surface. Other objects of the invention are to provide methods and means to attach said emulsion, after. exposure toactivating actinic radiations, to said surface; to provide means to develop out and fix said image onto said surface; to providemeans to develop out and cfix said image onto said 2,947,626 Patented Aug. 2, 1960 surface; and to provide for the glazing and firing of said surface in order to render said image permanently a part of said surface. Other objects will become obvious in the reading of the following description.

Generally, in carrying out the present invention, a gelatin base emulsion is provided sensitized in such manner as to be hardened by exposure to activating actinic radiations such as visible light and having incorporated therein ceramic pigments of desired color. It is believed unique to provide'a gelatine emulsion carrying a means for staining a ceramic surface and causing adhesion of the colored gelatine image thereto when the sensitized gelatine has been hardened in part by exposure to actinic radiations.

More specifically, and in the preferred manner of carrying out the present invention there is provided a new form of photographic printing medium having 'at least two layers or at least two strata of sensitized emulsion carried by a temporary support or backing, one layer or stratum being pigmented, and preferably of lower sensitivity to actinic radiations, and the other layer or stratum being unpigmented, and preferably of higher sensitivity to actinic radiations. Such a photographic printing medium is exposed to suitable activating radiations to so modify said emulsions that the multi-layer emulsion or stratified emulsion can be transferred to a porous ceramic base with the nnpigmented emulsion serving as a barrier to prevent unwanted absorption thereby to pig- Inent carried by the other pigmented layer or stratum. The image when so applied to the ceramic face can then be glazed by usual techniques of firing known in the ceramic art. i

While reference will be herein usually made to dua emulsions applied to a ceramic base and transferred thereto from a temporary support such as paper, it should be realized that in fact a single emulsion layer can equal-' ly becontemplated having at least two strata of different properties and in some instances three strata whereby to achieve the objects set forth as-hereinafter explained.

In preferred practice, two layers of gelatine based emulsion are used of different sensitivity factors with respect to activating radiations, one emulsion being pigmented and the other being unpigmented. However, the gelatine coating on the paper or like temporary support can equally be considered as a single layer of emulsion having different characteristics in different strata or areas since the two layers as applied to the backing or support, in accordance with the preferred procedure of this present invention must to some extent intermingle and intermix. In other words, the interface between the two layers will not be or may not be clearly defined but may be a zone above which a higher sensitivity, non-pigmented zone will exist and below which a lower sensitivity pigmented zone will exist. Furthermore, in preferred practice, a third layer of pigmented but unsensitized gelatine will be provided nearest the support face, to serve as a release stratum, when transferring the image from the paper backing to the ceramic surface.

Reference herein to a negative for normal photographic use is also to be construed as covering any translucent screen having at least one variation in density thereon or therein with respect to the passage there through of radiations which can cause modification in the solubility of a gelatine or like layer containing a photographic agent capable of causing such modification. It is obvious that variations of density per unit area of the emulsion during exposure to such radiations can also be achieved without a screen, using variations of light transmission for example.

In one mode of practicing the present invention an emulsion utilizing a gelatine base is first formed andis applied to a suitable temporary or intermediate back- 2,947,e2a a r a ing, such as paper. The film of emulsion is prepared by admixing gelatine sugar and water to which, in accordance with one feature of the present invention, there is added a quantity of. pigment of desired color and compatible with the gelatine mixture and preferably a quantity ofa conventional underglaze hinder or fixing medium such' as engobe, as used in the ceramic arts. This pig mented gelatine solution is applied to the paper or like support in unsensitized condition as by floating'on or by any usual coating method employed in the preparation ofphotographic printing paper. The layer of pigmented gelatine is then dried in a dust-free atmosphere, care being taken to set the film of gelatine quickly to obtain a uniform thickness of the layer. The paper support may be of any type having uniform absorbability overits face but preferably is. one which has a highly absorbent'but smooth surface and is sized or otherwisesurface treated to present a hard face whereby the transfer of the gelatine emulsion from the temporary paper support'to the ceramic suppo-rtat a later point will not be't'oo fast, ashereinafter brought forth.

The dried coated sheet is now ready for sensitizing. Another novel" and unique feature of the present invention is that the sensitizing process includes the application of another layer of gelatine carrying a sensitizer which isplaced over the first pigmented layer. To this end,v a solution is made of another portion of gelatine in water to which has been added a large quantity of potassium bichromate. Preferably, a saturated solution of potassium bichromate in water is used in proportions in the range of five. parts of bichromate solution to one part" of a gelatine. solution made up of one part of gelatinjet'o five parts of water. The paper backing carrying the layer of'pigmented. but unsensitized gelatine as a first emulsion coating is now immersed in the bichromate gelatine solution for a short period. of time to sensitize the first layer in part and to lay' down thereon a thin layer of highly sensitive gelatine as a second. unpigmented or clear emulsion coating.

' Itwill be realized that the'dual emulsion thus formed on the paper or like temporary support comprises a lower or first layer of sensitized emulsion which has been sensitizedonly to a partial depth due to the short contact time for sensitizing and the state of dryness of the layer. Over this there is arranged an upper layer or second layer of more highly sensitized emulsion. The coated paper is now dried in the absence of actinic radiation" andnthe sensitized photographic paper thus produced is ready for use in practicing the present invenfirm, where it. relates to the preparation of a photographic image on a ceramic surface. The emulsion is thus formed ofamulti-layer structure either as a dual layer, one layer being unpigmented but sensitized and the other layer being pigmented. and sensitized only to a major depth, or as a three-layer structure with a first pigmented unsensitized layer, a second pigmented sensitized layer and a top unpigmentedsensitized layer.

In the description herein given. reference is made to the'production of a printing photographic paper having two or more layers of emulsion of difierent characteristics; It should be understood however that it is not imperative to have. these layers as separate predefined laminary sections. In one form of carrying out the invention, the first or lower layer is formed of a gelatine base with suitable 'pigmentswith or without slip clay, en gobe' or other binder medium but without the use of a sensitizer. When the layer is applied to the desired support such as the exemplified paper and is allow to dry, at least to a tacky stage, the coated paper is immersed in a solutionv containing the sensitizer and more gelatine.

The sensitizer will thus penetrate into the lower layer of" gelatine to a degree which will not necessarily be to the full depth to render this light sensitive but will leave as an upper layer a more highly sensitized coating which may not be truly laminated in relation to the 4 lower layer but which will form an upper area or stratum of the gelatine emulsion, which has higher sensitivity than the stratum below for the purpose hereinafter described, and there will be a lowest stratum, nearest the paper face of pigmented but substantially unsensitized gelatine. Even should'this lowest stratum be sensitized, it will be to a much lesser degree than the stratum above it whereby there is provided alowest stratum of practically unsensitized gelatine.

Alternatively, the lower layer may be formed in con-- be' described in accordance with the novel teaching of" our invention. The dual-coated paper produced as defined above is exposed to suitable source of actinic radiation, such as a photo-flood lamp through an imagebearing negative. As is usual in all photographic processes, the time of exposure will be dependent upon the intensity of the source of radiation, the distance between thenegative and source of radiation and, if these two factors are fixed, the third variable is the density of the negative and the contrast thereof. After suitable exposure, such as 30 seconds to 17 minutes through the negative which will be fairly long since a potassium bichromate sensitized emulsion is being used and this is relatively slow, the negative is removed from the paper.

Thereafter, in accordance with a unique feature of the present invention, the photographic paper is further exposed to the direct rays of the source of actinic radiation for a burning-in of the upper or more highlysensitized layer for a short period of time, such asfrcm 5 seconds to one minute.

The purpose of such dual exposure is to obtain a hardened layer of gelatine over the whole surface of the exposed lower or less sensitive layer. As is Well known, potassium bichromate emulsions change color when ex'- posed to light and harden. The'amount of hardening is directly a function of the amount of light aliowed to penetrate the negative and thus the desired contrast of the positive image will be achieved by proper choice of time. However, when the emulsion is exposed a second time without the partial screening effect of the negative, an overall stratum of hardened gelatine will be formed.

This upper stratum or layer has the purpose, as hereinafter more specifically explained, of blocking out. on the final porous receiving surface such as a ceramic tile, those portions which are to be left free of color, namely, the whites or high-lights. Because of the extreme porosity of a ceramic surface, even when once fired to form a bisque, and the extreme affinity possessed by the'ceramic base forthe ceramic pigment, the hardened stratum of unpigmented gelatine will form a substantially colorless protective barri'erto such areas as are to be left unpigmented in the final formof the image.

The dual exposed paper is now ready for transfer to" the ceramic surface. Preferably, this surface'is rendered as smooth as possible since the quality of the final print on the surface can be no better than the texture of the receiving surface of bisque. It will be rendered free'of dirt, grease and stains. The paper is'immersed in Water at about F. fora few seconds, the excess water shaken oif' and the paper placed with the emulsion sid'e down into contact'with the'surfa'ce ofi't'ne bisque which is to receive the image. Direct register ofithe'image in the position it is to finally occupy'is' imperative at theoutset since the paper cannot now be moved or removed without destroying the image. Preferably; a good contact is by gentle smoothing pressure on the back of the paper with, for example, a small sponge wet with water. After a few seconds, contact pressure is stopped and the paper backing, which is exposed to view is covered by a piece of blotting paper or like absorbent material which has been soaked in water. Thereafter, heat is rapidly applied to the blotting paper of sufiicient amount to cause the water in the blotting paper to steam. Preferably, slight pressure is also applied, such as use of an electric iron to cause steaming and pressure.

After a few seconds by applying slight twisting motion on the tile or like surface, the tile will start to move and the necessary cleavage of the hardened stratum from the unsensitized stratum to cause the transfer has been made. Alternatively, when applying the image to other than an object which can be so twisted, trial and error techniques are used to determine the transfer time for a particular surface.

p The backing paper can now be slid off the applied image carrying with it the stratum or layer of pigmented, unsensitized emulsion and a solid mass of pigment and gelatine will be exposed to View on the tile representing gelatine held pigment, some being still in water soluble condition where no light has been allowed to contact the emulsion through the negative, while other parts will be hardened pigmented gelatine, which is insoluble to the action of water where light has penetrated the negative.

It will be also fully realized that an insoluble unpigmented layer which is now below the negative-exposed layer and which will be in direct contact with the face of the bisque exists as a barrier to prevent the pigment in the still Water soluble portions of the emulsion from being picked up by the porous ceramic surface, which, as mentioned before, has a great afiini-ty for the type of pigments chosen. Also, the break or fracture of the gelatine will have taken place along a cleavage plane or number of planes horizontally through the pigmented layer of gelatine where the sensitizing solution has penetrated only, so that the layer of gelatine transferred will be much thinner than the thickness of the original layer of pigmented gelatine having left behind a layer of pigmented unsensitized soluble gelatine which has not been hardened by exposure to the light; It is only now necessary to remove the water soluble emulsion areas by applying a wet fine grain sponge, such as a foam rubber sponge, using hot water. If desired, this operation may be performed under the rays of a heating lamp or like means of keeping the water soluble portions of the emul-' sion in a soft condition, conducive to easy sponging away. This operation must be performed in a quick, gentle manner to avoid disturbance of the insoluble portions of the emulsion now left on the bisque as a thin gelatine image, clearly delineated in the particular color of the ceramic pigment used.

When the coated bisque has thoroughly dried, a conventional glaze used for the 'final treatment of ceramic articles is applied by spray or brush over the whole area and the ceramic piece thus decorated can be fired for the time and temperature called for by the particular glaze chosen. Obviously, colored glazes can be used and any normal and usual procedure adopted for the final preparation of a decorated ceramic piece utilizing underglaze pigments. It will be found that the firing of the ceramic piece will in no way adversely affect the photographic image and due to the thinness of the image left on the ceramic surface, there will be no tendency for the glaze to pull away or break during firing.

Reference has solely been made .to the production and.

use of a dual emulsion or a differential zone emulsion hereinbefore for use in producing the image. However, the photographic printing sheet can be made with only the first layer of pigmented emulsion dulysensitized with potassium bichroma-te namely, without the upper, clear, unpigmented layer or stratum of emulsion. The proceii dure just described would then be followed with the omis sion of the second, direct light, exposure.

It is believed unique to provide a gelatine emulsion with ceramic pigment and with for example a ceramic engobe or like binder and accordingly, the invention embraces this feature. However, due to the extreme affinity of the porous surface of the bisque for the ceramic pigment it is extremely ditficult to prevent degradation of the highlights or clear portions when using the single emulsion technique and while certain artistic effects can be achieved by use thereof, it is preferred to control the contrast of the image and the blocking out of clear areas by means of the dual emulsion technique herein described. In like manner, reference has been made to the use of an unsensitized layer of gelatine as a third stratum or layer for the purpose of securing a quick release when transfer is made, but this can be dispensed with and either a paper can be used having a coating of a release medium or an underexposure of the emulsion can be carried out which will leave a substantially unhardened layer nearest the backing.

In order to more specifically define the present invention and to ascertain the manner in which it may be practiced, in one modification thereof, reference is made to the accompanying drawing and to the specific example of operation hereinafter given wherein all the figures are at enlarged scale in order to better illustrate the particular invention.

In the drawing:

Figure 1 is a greatly magnified cross-sectional view of a piece of photographic unexposed but sensitized paper bearing the unique emulsion according to one feature of the present invention;

Figure 2 is a plan view of a photographic negative of conventional form;

Figure 3 is a crosssectional view, at an enlarged scale, of a manner of exposing the paper of Figure l to actinic radiation through the negative of Figure 2;

Figure 4 is a cross-sectional view, at an enlarged scale, similar to Figure 3, but showing the unique burning-in of the emulsion, in accordance with another feature of the present invention, with the negative of Figure 2 removed;

Figure 5 is a cross-section of the exposed paper held in pressure contact with the ceramic base upon which the emulsion is to be transferred, by means of an electric iron;

And Figure 6 is an extremely enlarged cross-section of the finished ceramic piece having the image to be fired thereon in position, but before firing.

It should be understood that all of the figures of the drawing are somewhat diagrammatical, since the articles involved in this process cannot be reproduced in normal scale and in normal contour to adequately illustrate the present invention. For example, an original emulsion film as used on the paper backing in the present invention may be about .006 inch thick with the thickness of the tile to which part of this is transferred being 1 to /2 inch thick. Thus, a normal scale, actual, illustration would be of little use in demonstrating the invention.

Referring now to the drawings, the paper shown in Figure 1 will be made as follows:

Solution A.-A first gelatine solution was made by adding 8, grams of granulated gelatine to which was added, as a stabilizer, 23 grams of sugar to 40 grams of distilled water. The solution was thoroughly stirred and mixed using the water heated to about 190 F.

' Solution B.A pigmented solution was made by taking 43 grams of Solution A and mixing therewith at the same elevated temperature, with rapid stirring, 20 grams of an underglaze ceramic color, specifically that technically known as Sunbrite Black (manufactured by Stewart Clay Company, New York, N.Y.) which has a pigment therein and called an engobe medium. The solution is allowed:

to cool to about F.

Solution C.-sensitizer.-Meanwhile a sensitizer-solution was formed inaunique manner according to the present invention by incorporating into the remaining 23 gramspf SolutionA, 1.15 grams of asaturated solution of potassium ,biehromate in distilled water. The mixing was madeatatemperature of about 150 F. and thesolut-ion thus formed placed out of contact with activating radiationsand allowed to cool.

Coating-PAsmooth finish highly absorbent paper backing was selected, such as that used for backing decalcornanias. The hardness and calendering of the surface of the paper has a definite effect upon theease of transfer of the emulsion from the backing to the ceramic surface, a quick clean release of the exposed emulsion being desirable. The selected paper'was coated with Solution B by drawing the paper over the gelatine at about 125 F. and then setting the gelatine quickly by contacting a cold surface to the rear face of the paper. Usual precausions to maintain the emulsion coating dust free and bubble free were observed. The first layer thus formed was now dried slowly to prevent flow of surface. Thickness of the emulsion layer should be about .006 inch.

When the emulsion became tack-free and thus nearly dried it was sensitized to a predetermined depth by immersion of the paper and emulsion for to seconds in a container of sensitizing Solution C maintained at a temperature of 95 F., the treatment resulting in absorption from the outer face inwardly of the sensitizer and being in the absence of actinic radiation. The resultant coated sensitized photographic paper then was dried in the absence of actinic radiations, to produce a multi-layer emulsion on the backing sheet.

In Figure 1, the paper backing sheet is shown at 10, the first layer of emulsion is shown at 11 with the sensitized portion shown at 11a and the unsensitized portion at 11b and the second thin highly sensitized upper layer is shown at 12, providing multi-layer emulsion photographic printing sheet 13. It will be realized that the depth of penetration of the sensitizer to the dotted line A to form strata 11a and 11b can be controlled by the time and temperature of immersion.

Figure 2 illustrates in plan view a conventional film negative comprising a thin sheet of translucent or transparent material bearing an image. The negative 14 is shown as bearing a'simple design of a circle 15 which is clear and a field 16 therearound which is opaque. It is assumed as desired to reproduce a positive image from this negative on a surface of a ceramic tile, the design finally then comprising a large black circle on a clear white frame.

To produce the initial latent image in the emulsions 11 and 12 of the photographic paper 13 of Figure 1, reference is made to Figures 3 and 4. In Figure 3, the negative 14 has been superposed on the paper 13 in contact with the emulsion side thereof, as shown, and an exposure to actinic radiation is made through said negative by means of a source of illumination 17 comprising a conventional photoflood light 18 in a reflector 19. Exposure is made for desired density of the image and in the particular example where there are no gradua-tions of density or grey tones, a short exposure is satisfactory of 3 minutes with the photoflood placed at 10 inches away from the negative. With other negatives than the process negative used for illustrative purposes, times of from seconds to 17 minutes may be required at this distance using the photcilood lamp known to the trade as No. l flood.

After the 3 minute timing, the photoflood is cut off and the negative is taken away. The-already exposed paper 13 is now subjected to the direct rays of the photofiood for a few Seconds without the screening elfect of the negative as shown in Figure 4. The second exposure may be considered a burning-in of the second layer of emulsion 12 and, in accordance with the present invention, it is considered a unique feature in that by so doing the highlights or clear portions of the image will he pre vented from giving up their color to the porous ceramic. surface at the time of transfer.

The time of the second exposure ofFigure 4 is short being from 5 to 30 seconds exposure at 1,0 inches-with the same floodlamp unit 17. seconds exposing was sufficient. This blocking out of the highlights is diagrammatically shown by'comparing Figures 3 and 4. In Figure 3, only the area below the clear circle 15 of the negative has been changed in color and therefore the gelatine has hardened or become nonwater soluble only 'in that area. This will apply-to both. layers 11 and 12 of emulsion since they are each sensitized and thus the shaded areas 20 and 21 will be created. However, as clearly shown, there will be a line as at A which will separate the emulsion layer 11 into its two strata, above which line the zone of hardened gelatine 21 will be formed and below which line no hardening will take place. However, when the second exposure is made, as shown in Figure 4, the whole of the upper emulsion layer 12 will be hardened and the cross-hatched section 22 will be created of non-Water soluble gelatine. Since the exposure time is very short and since the upper layer 12 will be more highly sensitive to light than the lower layer, the effect shown in Figure 4 will be achieved without in any way destroying the latent image in the lower gelatine layer 11 and without materially darkening the color of the gelatine.

It should here be noted that the process of the present invention, inasfar as it relates to the exposure of the bichromate sensitized multi-layer emulsion printing paper here described differs from normal photographic procedures in that the under-exposed prints produced by the first exposure give the visual appearance of having'been over-exposed but upon the further second exposure of Figure 4, the definition will improve and the picture quality will be enhanced. Over-exposure in the first step of Figure 3 is to be avoided since the final print made for transfer will then possess poor adhering qualities and be too dark. If the line A is very low, some sensitizing of layer 1112 may exist and therefore over-exposure may slightly harden this layer and make desired cleavage at line A difficult. A correct balance between the first ex posure through the negative (Fig. 3) and the second burning-in exposure (Fig. 4) gives a desired balanceof density and contrast in the final transferred image. 1

The exposed paper is now ready for transfer to the ceramic surface to which the image is to be permanently adhered. The base upon which the gelatine emulsion is transferred is shown as a tile 23, the surface of which, has been cleaned and dried. A smooth bisqued tile is preferred since a smooth but porous face is desired of close grain, if the image is to be of good final definition and clarity.

Transfer is made by the use of water and steam for the purpose of causing cleavage within the area of line A. The exposed paper 13 of Figure 4 is immersed in water for a short time, such as 3 or 4 seconds, the water being warmed to about F. Excess water is shaken off and the paper is then placed, emulsion side down, in contact with the smooth face of the tile and is pressed in place. it is imperative that the emulsion be registered in the position it is to finally occupy on the tile at the first attempt, since once contact is established the image. will be harmed or destroyed if any attempt is made to? change its position. The paper backing 10 is now covered with a piece of wet blotting paper 24 of the same size as the backing, at least, and an electric iron 25 is then applied to the blotting paper. This is clearly shown in Figure 5. It will be noted that the upper layer 12 exposed to form a highlight blocking layer, is in directv In the specific case, .10 v

9 up its dye or stain to the tile, there is a non-water soluble layer 12 over the face of the tile acting as a barrier to unwanted pick up of pigment on portions which are to be left clear of color. The porous face of the tile has a great aflinity for the underglaze pigment mixture carried by the gelatine and without this protective barrier transfer of color to unwanted parts of the tile surface would take place.

p The iron 25 can be of the type "used in photographic mounting processes and its heat should be sufiicient to cause steaming of the water carried by the blotting paper. After a short period of time, such as 10 seconds, the transfer to the tile 23 can be accomplished by applying a slight twisting action thereto. When the tile starts to move under this action in about twenty seconds, transfer has taken place and the iron is removed and the paper backing 1t) and blotter 24 carefully slid off from the emulsion layers now carried by the tile 23. Alternatively, the hot iron may beremoved after a predetermined time limit such as 30 seconds established for the particular paper 13, experimentally, and the cleavage then established by a twisting movement.

The water soluble unhardened stratum of gelatine below line A will be softened by the steam and will readily break or cleave along the line of hardening established by exposing to light the sensitized portions above line A. In other words, portions below line A will stay on the temporary backing paper and portions above the line will transfer, the line A becoming more or less a line of cleavage except that the line may be quite wide and be more of a cleavage area or zone.

It is necessary now to remove the water soluble parts on the tile only the hardened image desired, as shown in Figure 6 where the hardened portions 21 and 22 are diagrammatically illustrated as adhering to tile 23.

It should be realized that the thin barrier layer 22 shown in Figure 6 will have been exposed for too short a time to have materially changed color and since this original layer is made from emulsion containing no pigment it will present a thin practically colorless film or membrane over'the areas which are to be left untinted by color such as highlights, borders, white objects and the like. Thus, this film 22 serves to preserve the maximum contrast of the final print without sullying same or degrading the highlights despite the affinity of the tile surface to the mixture of underglaze pigment and engobe medium as the tinting or staining means.

The piece illustrated in Figure 6 is now treated with a conventional glaze used for ceramicsas by spraying or brushing and the piece is then fired in the usual way at the temperature determined by the glaze selected. The total image comprising the emulsions 21 and 22 is too thin to cause any problem inthe firing such as uneven firing or isolated unglazed areas.

Instead of using an iron 25, the unit of Figure can be placed blotter side down on a hot plate, or infra-red heat can be used. Other obvious modifications of the illustrated specific procedure can be adopted. Also, the underglaze can be of any desired color and the final glazing can also be in a transparent color glaze medium if desired.

If an outside border is desired around the image or other stopping out is to be effected, this can be done by using a commercial liquid rubber mask painted or otherwise applied to the tile. Alternatively, a second burning in as in Figure 4 but with a suitable stop-out negative protecting the major image 21 can be employed to give a dark border around the print. Finally, if care is used in selecting the right exposure for the second light treat 'ifi ment of Figure 4, a border can be burned-in using the upper non-pigmented layer 12. Any excessive exposure in the arrangement of Figure 4, without or with a mask or other stop-out device, may render portions of the lower emulsion 11 insoluble under this border area and give the result of a gray or mid-tone border around the final print.

Modifications in the quantities of gelatine and/or pigment used in the formation of the emulsions can be varied to suit conditions of working and conventional techniques known in photographic arts can be utilized to varying the efiect achieved by the present invention. Other modifications in the technique of producing the new form of printing medium of the present invention are obvious. For example, while the sensitizing of the various layers or strata of the emulsion has been proposed by using the second gelatine solution to sensitize the first, it is obvious that the first layer or coating can be itself sensitized before. applying it to the backing and the second layer can also have its own degree of sensitizing. By this modification any degree of relative sensitivity of the two layers can be achieved to suit specific requirements. Different sensitizers can be used also in the respective sensitized layers as long as they are compatible with each other. In such an instance, a lower clear gelatine layer without sensitizer, forming a layer 11b (Fig. 1) may be formed to assist in easy cleavage and transfer, although no such layer is essential to the invention. In practice, a paper or like backing which has been sized with a water soluble substance, for example, can be used to give release of the emulsion after exposure by use of the steam from the blotting paper. However, in the preferred procedure, a release film of preferably gelatine is provided.

Furthermore, the present invention contemplates the useof other than the light source 17 for exposing the image. Infra red or X-ray radiations can be used for example. Where actinic radiations are referred to hereinbefore, there is intended such radiations which can afiect the condition of water solubility of a gelatine layer to which a suitable reactant has been added for this purpose.

Any color can be used in the form of ceramic pigment it only being necessary to select those chemical compounds so used which will not have any elfect on the gelatine under exposure to light or other radiation. Some chromium containing compounds may eifect the gelatine deleteriously by causing an overall hardening and yet be suitable ceramic pigments. These will be avoided in practice and conventional substitutes utilized which do not contain chromium salts. Likewise, metallic elements in uncombined form can be used, such as gold and silver in pigment form, as presently utilized for ceramic decoration. Such pigments are not water soluble as a rule but I are carried by well known binders such as engobe medium and can be dispersed through the gelatine by stirring the mixture in warm aqueous solution.

It should be also realized that one of the problems which has been existent with respect to the use of a photographic image on a tile to be fired has been that the image has usually been considered to be too thick, at

least in its densest parts to permit firing of a glaze thereover but this has been accomplished in accordance with one feature of-the present invention by using a thin final image which can readily be fired. This coupled with the provision of a blocking out layer of emulsion for preserving clean highlights and other portions to be left unpigmented, provides a new and useful specific artifact in the photographic and ceramic arts.

What is claimed is:

1. The process of producing a photographic image on the surface of a ceramic piece comprising forming a first sensitized emulsion of a gelatine base containing ceramic pigment which has no hardening eifect on said gelatin base and applying same to a temporary support, forming a second non-pigmented sensitized emulsion over said first emulsion, both emulsions being sensitized with potassium bichromate, exposing said emulsions to actinic radiations at varying degrees of intensity per unit area over the surface of the emulsionsfor a first exposure for a period of time sufficient to obtain a desired density of the resultant image in the first emulsion, exposing, said emulsions to actinic radiations of the same degree of intensity per unit area over the surface of. the emulsions for a second exposure for a period of time much smaller than the first exposure, to harden said second 'unpigmented' emulsion and form a highlight blocking film, transferring said emulsionsfrom said temporary support onto a porous surface of the ceramic piece with. the second emulsion incontact with said surface, washing awaythestill soluble.

portions of said first emulsion, to leave a hardened unpig mentcd film over said surface of said second emulsion. and hardened pigmented parts of said first emulsion forming an image bonded to said surface, and drying the image.

2. The process according to claim 1 in which the transfer of the emulsions is performed by sensitizing said first emulsion to a predetermined depth only leaving a pigmented unsensitized stratum of gelatine next to said support and cleaving said unsensitized stratum from saidsensitized and hardened layer using steam to leave a thin emulsion image on said ceramic surface which can be glazed and fired.

3'. The process of reproducing a photograph on a porous face of a ceramic piece comprising in combination preparing a photographic paper by coating a backing sheet. with a first. layer of hot gelatine solution containing pigment of desired color and having no adverse hardening effect on gelatin, cooling and drying the layer to tackiness, coating said backing paper and layer with a hot gelatine solution containing a large quantity of a saturated solution of potassium bichromate, in order to sensitize the first layer to at least a major depth and leave a thin sensitized gelatine layer of unpigmented emulsion as the upper surface of the photographic sheet, cooling and drying the sheet, exposing the finished sheet to light through a design-bearing screen for a period of time necessary to develop in said first emulsion layer a desired density image in the sensitizer portion corresponding to said design with the gelatine hardened where the light penetrates and in proportion to the degree of penetration, exposing the sheet a second time without the presence of thedesign-bearing screen for a short period of time necessary to harden all of the second unpigmented layer of emulsion to form a barrier to the passage of pigment therethrough, immersing the exposed sheet in warm water, placing same in contact with the porous ceramic surface which is to receive the image with. the emulsion side in contact with said surface, applying excess water to the backing paper by means of a wet piece of absorbent paper, applying suflicient heat to said backing paper by means of an electric iron to create steam to assist the transfer of the emulsion from the backing paper to the ceramic surface by cleaving the unsensitized emulsion from the sensitized emulsion of said first layer, removing the backing paper, sponging oif the water soluble parts of the emulsion now carried by the ceramic surface, drying the ceramic piece now carrying the thin pigmented hardened gelatine image, ap-

plying a coating of ceramic glaze over-the image and the ceramic surface and firing the glaze to render the, image permanently bonded to. the ceramic piece.

4. The. process of reproducing a photograph on a porous face of a ceramic piece comprising incombination preparing a photographic sheet by coating a backingpa per with afirst' layer of hot gelatine solution containing. ceramic pigment of a't'ype which has no adverse hardening, effect. on gelatin, of desired. color, cooling and drying the layer to tackiness, coating, the paper and layer with a second hot gelatine solution containing a large quantity of a saturatedsolution ofpotassium bichromate, in. order to sensitize the first layer through part of its depth leaving: a sensitizedgelatine layer of unpigmented emulsion. as the upper. surface of the photographic sheet, coolingand' drying the sheet, exposing the finished sheet to light through a design-hearing screen for an exposure period to develop insaid first emulsion layer a desired density image in the. sensitized portion corresponding to said design with the gelatine hardened where the light penetrates, exposing the sheet a second time without the presence of the design-bearing screen for a short period exposure time to harden all of the second unpigmented layer of emulsion to form a barrier to the passage of pigment therethrough, immersing the doubly-exposed, sheet in warm water, placingv same in contact with the porous ceramic surface which is to receive the image with the emulsion side in contact with said surface, applying excess water to the backing paper by means of a. wet piece of absorbent paper thereof, applying sufficient heat to said backing sheet by means of an electric iron to create steam to assist the transfer of the emulsion from the backing paper to the ceramic surface by cleaving the unsensitized emulsion from the sensitized. emulsion of said first layer, removing the backing paper, sponging ott the water soluble parts of the emulsion carried by the ceramic surface, drying the ceramic piece now carrying the thin pigmented hardened gelatine image, applying a coating of ceramic glaze over the image. and the ceramic surface and firing the glaze to render the image permanently bonded to the ceramic piece.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Photo Ceramics, Ceramic Industry, pages 54 and 55. 

1. THE PROCESS OF PRODUCING A PHOTOGRAPHIC IMAGE ON THE SURFACE OF A CERAMIC PIECE COMPRISING FORMING A FIRST SENSITIZED EMULSION OF A GELATINE BASE CONTAINING CERAMIC PIGMENT WHICH HAS NO HARDENING EFFECT ON SAID GELATIN BASE AND APPLYING SAME TO A TEMPORARY SUPPORT, FORMING A SECOND NON-PIGMENTED SENSITIZED EMULSION OVER SAID FIRST EMULSION, BOTH EMULSIONS BEING SENSITIZED WITH POTASSIUM BICHROMATE, EXPOSING SAID EMULSIONS TO ACTINIC RADITIONS AT VARYING DEGREES OF INTENSITY PER UNIT AREA OVER THE SURFACE OF THE EMULSIONS FOR A FIRST EXPOSURE FOR A PERIOD OF TIME SUFFICIENT TO OBTAIN A DESIRED DENSITY OF THE RESULTANT IMAGE IN THE FIRST EMULSION, EXPOSING SAID EMULSIONS TO ACTINIC RADIATIONS OF THE SAME DEGREE OF INTENSITY PER 